This application claims priority to United States Provisional Patent Application No. 61/319,733, filed March 31, 2010.

The present application relates to heat exchangers.

Vapor compression systems are commonly used for refrigeration and/or air conditioning and/or heating, among other uses. In a typical vapor compression system, a refrigerant, sometimes referred to as a working fluid, is circulated through a continuous thermodynamic cycle in order to transfer heat energy to or from a temperature and/or humidity controlled environment and from or to an uncontrolled ambient environment. While such vapor compression systems can vary in their implementation, they most often include at least one heat exchanger operating as an evaporator, and at least one other heat exchanger operating as a condenser.

In systems of the aforementioned kind, a refrigerant typically enters an evaporator at a thermodynamic state (i.e., a pressure and enthalpy condition) in which it is a subcooled liquid or a partially vaporized two-phase fluid of relatively low vapor quality. Thermal energy is directed into the refrigerant as it travels through the evaporator, so that the refrigerant exits the evaporator as either a partially vaporized two-phase fluid of relatively high vapor quality or a superheated vapor.

At another point in the system the refrigerant enters a condenser as a superheated vapor, typically at a higher pressure than the operating pressure of the evaporator. Thermal energy is rejected from the refrigerant as it travels through the condenser, so that the refrigerant exits the condenser in an at least partially condensed condition. Most often the refrigerant exits the condenser as a fully condensed, subcooled liquid.

Some vapor compression systems are reversing heat pump systems, capable of operating in either an air conditioning mode (such as when the temperature of the uncontrolled ambient environment is greater than the desired temperature of the controlled environment) or a heat pump mode (such as when the temperature of the uncontrolled ambient environment is less than the desired temperature of the controlled environment). Such a system may require heat exchangers that are capable of operating as an evaporator in one mode and as a condenser in an other mode.

US 2006/0162917 A1 discloses a heat exchanger for carbon dioxide, in which a tank having a number of domes is coupled with a header and a connection member having a connection flow channel which is interposed between the header and the tank. Thereby, it is easy to change a refrigerant flow channel. Further, this reduces the volume of a header tank, and improves productivity, pressure resistance and durability.

US 2005/0217838 A1 discloses an evaporator for an air conditioning apparatus which has an upper and a lower tank and multiple tubes vertically extending and respectively connected to the tanks at upper and lower ends. A fluid passage portion is formed in the lower tank. Multiple drainage recesses are formed in the lower tank at such portions, at which the recesses do not interfere with the fluid passage portion.

The invention provides a heat exchanger including first and second sequential flow passes for a fluid, and a header structure to fluidly connect the first and second sequential flow passes. The first flow pass comprises a first plurality of parallel arranged tubes, each having two opposing broad flat sides joined by two opposing narrow sides. The second flow pass comprises a second plurality of parallel arranged tubes, each having two opposing broad flat sides joined by two opposing narrow sides. The header structure comprises a first plate having a first planar face approximately perpendicular to the opposing broad flat sides of the first and second plurality of parallel arranged tubes and a second plate having a second planar face parallel to and joined to the first planar face. The first and second plates together define a flow conduit between a first one tube of the first flow pass and a second one tube of the second flow pass. The flow conduit is at least partially defined by an arcuate profile in one of the first and second plates, the arcuate profile defining an axis substantially parallel to the first and second planar faces. The axis is a first axis, and the flow conduit is further at least partially defined by an arcuate profile in the other of the first and second plates. The arcuate profile in the other of the first and second plates defines a second axis substantially parallel to the first and second planar faces, and is located within a plane parallel to and approximately midway between the opposing broad flat sides of at least one of the first one tube and the second one tube.

The axis is located within a plane parallel to and approximately midway between the opposing broad flat sides of at least one of the first one tube and the second one tube.

The axes are located within the plane defined by the first and second planar faces. In some embodiments the first axis may be coincident with the second axis.

Some embodiments of the invention provide a first tube slot in one of the first and second plates to receive an end of the first one tube therein, and provide a second tube slot in one of the first and second plates to receive an end of the one second tube therein. In some embodiments the edges of the first and second tube slots are offset from the first and second planar faces.

In some embodiments the first tube slot includes a tapered lead-in for assembly of the one first tube therein. In some embodiments the second tube slot includes a tapered lead-in for assembly of the one second tube therein.

In some embodiments the edges of one or both of the first and second tube slots are offset from the first and second planar faces by an amount greater than the outer radius of the arcuate profile.

• FIG. 1 is a perspective view of a heat exchanger according to an embodiment of the invention.
• FIG. 2 is a detail view of the portion bounded by the line II-II of FIG. 1.
• FIG. 3 is a plan view of the portion of the embodiment shown in FIG. 2.
• FIG. 4 is a sectional view along the lines IV-IV of FIG. 2.
• FIG. 5 is a sectional view along the lines V-V of FIG. 2.
• FIG. 6 is a partial perspective view of a header structure of the heat exchanger of FIG. 1.
• FIG. 7 is a sectional view along the lines VII-VII of FIG. 6.
• FIG. 8 is a partial perspective view of a header structure for use in another embodiment not part of the invention.
• FIG. 9 is a sectional view along the lines IX-IX of FIG. 8.
• FIG. 10 is a partial perspective view of a header structure for use in another embodiment of the invention.
• FIG. 11 is a sectional view along the lines XI-XI of FIG. 10.
• FIG. 12 is an exploded partial perspective view of a heat exchanger according to another embodiment of the invention.
• FIG. 13 is a partial perspective view of a tube and fins for use in some embodiments of the invention.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

FIGs. 1-7 illustrate an exemplary embodiment of a heat exchanger 10 according to the present invention. In some applications the heat exchanger 10 may be used as an evaporator in a vapor compression based climate control system. In other applications the heat exchanger 10 may be used as a condenser in a vapor compression based climate control system. In still other applications the heat exchanger 10 may operate both as a condenser in a first mode of operation, and as an evaporator in a second mode of operation. In still other applications the heat exchanger 10 may find utility in other type of systems such as, for example, a Rankine cycle power generation system.

Referring to FIGs. 1 and 2, the heat exchanger 10 includes a first flow pass 12 comprising a plurality of tubes 14a arranged in parallel and a second flow pass 16 comprising a plurality of tubes 14b arranged in parallel. The tubes 14a of the first flow pass 12 include an inlet end 18a and an outlet end 20a. The inlet ends 18a are adjacent a first header 22, which is tubular in the illustrated embodiment and the outlet ends 20a are adjacent a return header 24 such that the tubes 14a extend from the first header 22 at a first end 26 of the heat exchanger 10 to the return header 24 at a second end 28 of the heat exchanger 10 opposite the first end 26. The tubes 14b of the second flow pass 16 include an inlet end 18b and an outlet end 20b. The inlets ends 18b are adjacent the return header 24 and the outlet ends 20b are adjacent a second header 30, which is tubular in the illustrated embodiment, such that the tubes 14b extend from the return header 24 to the second header 30, which is located at the first end 26 of the heat exchanger 10. The first header 22 includes a first fluid port 36 that defines an inlet of the heat exchanger 10 and the second header 30 defines a second fluid port 38 that defines an outlet of the heat exchanger 10. The first fluid port 36 and the second fluid port 38 provide a means for connecting the heat exchanger 10 into a system.

In this arrangement, the first and second flow passes 12 and 16 are sequential to one another so that a fluid (for example, a refrigerant) may be directed to flow into the heat exchanger 10 by way of the first fluid port 36, flow through the first flow pass 12 from the first header 22 to the return header 24, flow through the second flow pass 16 from the return header 24 to the second header 30, and flow out of the heat exchanger 10 by way of the second fluid port 38. It should be understood, however, that the fluid might similarly enter the heat exchanger 10 by way of the second fluid port 38 and exit the heat exchanger 10 by way of the first fluid port 36, so that the flow through the heat exchanger 10 is reversed and the fluid encounters the flow passes 12 and 16 in an order that is the reverse of the above.

Referring to FIG. 1, some embodiments of the heat exchanger 10 may include one or more optional baffles 42 in one or both of the headers 22, 30. These baffles 42 serve to separate the internal chamber of the headers 22 and 30 into two or more manifolds. Additional sequential passes for the fluid can thereby be provided for without requiring additional rows of parallel arranged tubes 14a or 14b.

Referring to FIG. 2, fins 46 may be arranged between adjacent ones of the tubes 14a and 14b. Although the exemplary fins 46 are of a serpentine convoluted type, any type of fins regularly used and known in the art can be similarly employed. The fins 46 can be used to provide surface area enhancement and/or flow turbulation in order to improve the rate and extent of heat transfer between the fluid passing through the tubes 14a, 14b and another fluid, such as for example air, passing over the outer surfaces of the tubes 14a, 14b. The fins 46 may alternatively or in addition provide beneficial spacing and/or structural support to the tubes 14a, 14b.

In some embodiments the fins 46 may be of sufficient depth to be common to a tube 14a in the first flow pass 12 and a tube 14b in the second flow pass 16, as shown in FIG. 2. In other embodiments, such as is shown in FIG. 13, the fins 46 may have a depth that is only sufficient for a single tube 14a so that separate fins 46 are used for the tubes 14a and the tubes 14b. The fins 46 are optional, however, and need not be present at all in a heat exchanger embodying the present invention.

As best seen in FIG. 13, the tubes 14a, 14b of the exemplary embodiment include two opposing broad flat sides 50 joined by two opposing narrow sides 52. Internal webs 54 may be provided inside the tubes 14a and 14b in order to divide the internal space of the tube 14a, 14b into a plurality of internal flow channels 56. The webs 54 may provide heat transfer augmentation as well as structural support for the tube 14a, 14b. Such structural support may be especially beneficial in vapor compression systems, wherein the fluid passing through the tubes 14a and 14b may be at an operating pressure that is substantially elevated in comparison to the pressure external to the tubes 14a and 14b.

Referring to FIGs. 2-4, the return header 24 includes a first plate 60 and a second plate 62. A planar face 64 of the first plate 60 is mated to a planar face 66 of the second plate 62. The mated planar faces 64, 66 are located on a plane 68 that is approximately perpendicular to the broad flat sides 50 of the tubes 14a, 14b.

Together the plate 60 and the plate 62 define a plurality of flow conduits 70, each providing a fluid connection between one of the tubes 14a and one of the tubes 14b. By connecting the flow passes in this manner, redistribution of a partially vaporized fluid over the multiple tubes 14b can be advantageously avoided when the heat exchanger 10 is operating as an evaporator.

In the exemplary embodiment of FIGs. 1-7, a flow conduit 70 is at least partially defined by an arcuate recess 72 that extends from the planar face 66 of the second plate 62 and by an arcuate recess 74 that extends from the planar face 64 of the first plate 60. The arcuate recesses 72 and 74 in one or both of the plates 60 and 62 can provide increased durability to the heat exchanger 10 when functioning at elevated pressures, as may be commonly encountered in both evaporators and condensers, as well as in other heat transfer functions for which the heat exchanger 10 may be utilized.

Continuing with the exemplary embodiment of FIGs. 1-7, the arcuate recess 72 of the second plate 62 has a radius of curvature 76. The radius of curvature 76 is measured about an axis 78 that is generally parallel to the planar faces 64 and 66 of the first plate 60 and the second plate 62, respectively. The arcuate recess 74 of the first plate 60 has a radius of curvature 80 measured about an axis 82 that is generally parallel to the planar faces 64 and 66 of the first plate 60 and the second plate 62, respectively. Both axes 78 and 82 are located in a plane 84 that is parallel to and approximately midway between the opposing broad flat sides 50 of one of the tubes 14a, 14b that is in fluid communication with the conduit 70. In the illustrated embodiment, the axis 78 and the axis 82 are located within the plane 68, as shown in FIG. 5. In some embodiments, however, one or both of the axes 78, 82 may be in a plane that is parallel to, but offset from, the plane 68. Although the axes 78 and 82 are shown as being coincident, they may be non-coincident in some embodiments.

Referring to FIG. 5, the first plate 60 includes a plurality of tube slots 86 to receivably engage the tubes 14a, 14b. The tube slots 86 are arranged in pairs, each pair corresponding to a tube 14a, a tube 14b, and a single flow conduit 70 to provide for fluid communication between the internal flow channels 56 of the tube 14a and the flow conduit 70 and between the internal flow channels 56 of the tube 14b and the flow conduit 70.

Edges 88 defined by the tube slots 86 are offset from the plane 68 so that a tube 14a, 14b can extend into a flow conduit 70 without substantially blocking the conduit 70. In order to provide for greater ease of insertion of the tubes 14a, 14b into the tube slots 86, a tapered lead-in 90 can be provided for each of the tube slots 86.

FIGs. 8 and 9 illustrate an alternative embodiment, not part of the present invention, of the return header 24 of FIGs. 1-7. The return header 24' illustrated in FIGs. 8 and 9 uses a modified plate 60' in place of the plate 60 found in the header structure 60 of FIGs. 1-7. The plate 60' does not include the arcuate recess 74 of the plate 60. In the embodiment of FIGs. 8 and 9, the edges 88' of the tube slots 86' are located in a common plane 92' that is parallel to and offset from the plane 68'. In this manner a tube 14a, 14b, could still be received in a tube slot 86' without substantially blocking the conduit 70'.

FIGs. 10 and 11 illustrate yet another alternative embodiment of the return header 24 of FIGs. 1-7. The return header 24" of FIGs. 10 and 11 includes a plate 60" in place of the plate 60 of the header 24 of FIGs. 1-7. The plate 60" includes an arcuate recess 74" having a radius of curvature 80" measured to an outer surface 94" of the plate 60". The plate 60" also provides the common plane 92" for the edges 88" of the tube slots 86". In this embodiment the perpendicular distance 96" between the plane 68" and the plane 92" is greater than the radius of curvature 80" of the arcuate recess 74".

A heat exchanger 110 according to another embodiment not part of the invention is illustrated in FIG. 12. The heat exchanger 110 includes a first flow pass comprising a first plurality of parallel arranged tubes 114a, and a second flow pass comprising a second plurality of parallel arranged tubes 114b. A header structure 124 fluidly connects the first flow pass to the second flow pass and comprises a first plate 160 and a second plate 162. A planar surface 164 of the plate 162 mates with a planar surface 166 of the plate 160. The plate 160 includes a first plurality of tube slots 186 corresponding to ends of the tubes 114a and the plate 162 similarly includes a second plurality of tube slots 186 corresponding to ends of the tubes 114b. Each of the tubes 114a and 114b include a 90 degree bend section 198 immediately adjacent to the header structure 124.

Various alternatives to certain features and elements of the present invention are described with reference to specific embodiments of the present invention. With the exception of features, elements, and manners of operation that are mutually exclusive of or are inconsistent with each embodiment described above, it should be noted that the alternative features, elements, and manners of operation described with reference to one particular embodiment are applicable to the other embodiments.